Showing papers on "Ullage published in 2014"

The Liquid Argon Purity Demonstrator

Abstract: The Liquid Argon Purity Demonstrator was an R&D test stand designed to determine if electron drift lifetimes adequate for large neutrino detectors could be achieved without first evacuating the cryostat. We describe here the cryogenic system, its operations, and the apparatus used to determine the contaminant levels in the argon and to measure the electron drift lifetime. The liquid purity obtained by this system was facilitated by a gaseous argon purge. Additionally, gaseous impurities from the ullage were prevented from entering the liquid at the gas-liquid interface by condensing the gas and filtering the resulting liquid before returning to the cryostat. The measured electron drift lifetime in this test was greater than 6 ms, sustained over several periods of many weeks. Measurements of the temperature profile in the argon, to assess convective flow and boiling, were also made and are compared to simulation.

Ignition experiments and models of a plastic bonded explosive (PBX 9502)

Abstract: Ignition experiments from various sources, including our own laboratory, have been used to develop a simple four-step, pressure-dependent ignition model for PBX 9502, which is composed of 95% by mass triaminotrinitrobenzene (TATB) and a 5% by mass chlorotrifluoroethylene/vinylidine fluoride binder. The four-steps include drying, mono-furazan formation, and decomposition of mono-furazan and TATB into equilibrium products. Our experiments were both sealed and vented and included various ullage percentages ranging from 18% to 75% of unfilled confinement volume. Our sample densities ranged from 38% of the theoretical maximum density (TMD) to 98% TMD. We observed a decrease in ignition times with the higher density samples, an increase in ignition times with increased venting, and an increase in ignition times with increased ullage. From our experiments, we conclude that decomposition of PBX 9502 is pressure dependent, open pore decomposition occurs in low-density experiments, and that closed pore decomposition occurs when the samples are pressed to near full density. In some of our confined high-density experiments we have observed for the first time, multiple temperature excursions prior to ignition caused by internal pressure generation.

Aircraft fuel tank ullage gas management system

Abstract: An aircraft fuel tank ullage gas management system is disclosed. The system includes an electrochemical cell having a membrane electrode assembly that includes a cathode and anode separated by an electrolyte separator. A cathode fluid flow path is in fluid communication with the cathode, and receives the flow of cabin air from the cabin air fluid flow path and discharges nitrogen-enriched air. An anode fluid flow path is in fluid communication with the anode, and discharges oxygen or oxygen-enriched air. The electrochemical cell also includes water in fluid communication with the anode. The system includes an electrical power source and electrical connections to the anode and cathode for providing an electric potential difference between the anode and cathode. An ullage flow path receives nitrogen-enriched air from the cathode fluid flow path and delivers it to the fuel tank. An optional flow path delivers humidified oxygen-enriched air back to the cabin.

Method and system for reducing the flammability of fuel-tanks onboard an aircraft

Abstract: A fuel vapor removal method for an aircraft includes removing an ullage mixture from ullage of a fuel tank of an aircraft, exposing the ullage mixture to adsorption media on the aircraft to reduce its fuel-air ratio, and returning the reduced fuel-air ratio ullage mixture to the fuel tank. A fuel vapor removal system onboard an aircraft includes a fuel tank, having ullage containing an ullage mixture, a pumping device, configured to pump the ullage mixture in a closed loop from the fuel tank ullage and back, an adsorption system, interposed in the closed loop, and a controller, including a microprocessor and system memory. The adsorption system includes an adsorber having adsorption media capable of adsorbing fuel vapor from the ullage mixture, and the controller is programmed to activate the pumping device, to pump the ullage mixture from the ullage, through the adsorption system, and return a reduced fuel-air ratio ullage mixture back to the ullage.

Self-Pressurization and Spray Cooling Simulations of the Multipurpose Hydrogen Test Bed (MHTB) Ground-Based Experiment

Abstract: This paper presents a CFD (computational fluid dynamics) model for simulating the self-pressurization of a large scale liquid hydrogen storage tank. In this model, the kinetics-based Schrage equation is used to account for the evaporative and condensing interfacial mass flows. Laminar and turbulent approaches to modeling natural convection in the tank and heat and mass transfer at the interface are compared. The flow, temperature, and interfacial mass fluxes predicted by these two approaches during tank self-pressurization are compared against each other. The ullage pressure and vapor temperature evolutions are also compared against experimental data obtained from the MHTB (Multipuprpose Hydrogen Test Bed) self-pressurization experiment. A CFD model for cooling cryogenic storage tanks by spraying cold liquid in the ullage is also presented. The Euler- Lagrange approach is utilized for tracking the spray droplets and for modeling interaction between the droplets and the continuous phase (ullage). The spray model is coupled with the VOF (volume of fluid) model by performing particle tracking in the ullage, removing particles from the ullage when they reach the interface, and then adding their contributions to the liquid. Droplet ullage heat and mass transfer are modeled. The flow, temperature, and interfacial mass flux predicted by the model are presented. The ullage pressure is compared with experimental data obtained from the MHTB spray bar mixing experiment. The results of the models with only droplet/ullage heat transfer and with heat and mass transfer between the droplets and ullage are compared.

Method and apparatus for automatically monitoring fuel tank ullage in an automated fuel authorization program

Abstract: Described herein is a fuel authorization program that vehicles enrolled in the fuel authorization program to provide fuel tank sensor data in each fuel authorization request, so that an amount of fuel authorized will be limited to the amount needed to fill the vehicle's fuel tank, reducing a likelihood that fuel will be diverted. In at least some embodiments, the fuel authorization controller at the vehicle automatically uses the fuel tank sensor data and known tank size to include in a fuel authorization request sent to a fuel vendor data defining how much fuel is required to fill the vehicle fuel tanks. In at least some embodiments, the fuel vendor consults data from a source other than the vehicle (such as records maintained by the fuel authorization program) to determine how large the vehicles fuel tanks are, and to calculate how much fuel is required.

Aircraft inerting system

Abstract: A method of controlling a flow rate of inerting gas introduced into a vented aircraft fuel tank, the method comprising: monitoring changes in a quantity of a fuel in the aircraft fuel tank; monitoring changes in the ambient air pressure external to the aircraft fuel tank; and actively controlling a flow rate of inerting gas, m(I), introduced into the aircraft fuel tank based upon changes in the quantity of fuel in the fuel tank and changes in the ambient air pressure, p. Also, an aircraft including a vented fuel tank, a supply of inerting gas for rendering inert the fuel tank ullage, and a controller for performing the method.

The Liquid Argon Purity Demonstrator

Abstract: The Liquid Argon Purity Demonstrator was an R&D test stand designed to determine if electron drift lifetimes adequate for large neutrino detectors could be achieved without first evacuating the cryostat. We describe here the cryogenic system, its operations, and the apparatus used to determine the contaminant levels in the argon and to measure the electron drift lifetime. The liquid purity obtained by this system was facilitated by a gaseous argon purge. Additionally, gaseous impurities from the ullage were prevented from entering the liquid at the gas-liquid interface by condensing the gas and filtering the resulting liquid before returning to the cryostat. The measured electron drift lifetime in this test was greater than 6 ms, sustained over several periods of many weeks. Measurements of the temperature profile in the argon, to assess convective flow and boiling, were also made and are compared to simulation.

Numerical investigation of pressurization performance in cryogenic tank of new‐style launch vehicle

Abstract: The pressurization performance of cryogenic tanks during discharge is investigated by a computational fluid dynamic approach. A series of cases accounting for the effects of various influence factors such as inlet gas temperature, ramp time of inlet gas temperature, wall thickness, outflow rate, injector structure, and liquid supercooling on pressurization behaviors are computed and analyzed successively. Several valuable conclusions have been drawn as follows: (1) Increasing inlet gas temperature, applying a thin wall to construct the tank, and increasing the outflow rate are beneficial to the reduction of gas requirements, (2) Ramp process and use of a straight pipe injector may lead to an excessive pressure drop at the beginning of discharge, (3) Use of straight pipe injector can remarkably reduce the gas requirement but lead to a large loss of liquid propellant as well as a large weight of final ullage gas, and (4) The mode of mass transfer within the tank is close related to the injector structure and liquid supercooling. A trend of mass transfer toward evaporation can be observed by increasing the liquid temperature, especially for the straight pipe injector case. Generally, the results of this paper might be beneficial to the design and optimization of a pressurization system. © 2013 Curtin University of Technology and John Wiley & Sons, Ltd.

System and methods for ullage space fuel level estimation

Abstract: A method for a vehicle, comprising: indicating a true fill level of a fuel tank based on a fuel vapor canister temperature profile during a refueling event. In this way, a quantity fuel dispensed over the maximum fill level of the fuel tank may be accounted for, regardless of the fuel level sensor reading.

A CFD model for the Multipurpose Hydrogen Test Bed (MHTB) Ground-Based Self-Pressurization and Pressure Control Experiments

Abstract: This paper presents a CFD model for simulating the self-pressurization of a large scale liquid hydrogen storage tank. In this model, the kinetics-based Schrage equation is used to account for the evaporative and condensing interfacial mass flows. Laminar and turbulent approaches to modeling natural convection in the tank and heat and mass transfer at the interface are compared. The flow, temperature, and interfacial mass fluxes predicted by these two approaches, during tank self-pressurization, are compared against each other. The ullage pressure and vapor temperature evolutions are also compared against experimental data obtained from the MHTB self-pressurization experiment. A CFD model for cooling cryogenic storage tanks by spraying cold liquid in the vapor region is also presented. The Euler-Lagrange approach is utilized for tracking the spray droplets and for modeling interaction between the droplets and the continuous phase (vapor). The spray model is coupled with the VOF model by performing particle tracking in the vapor, removing particles from the vapor domain when they reach the interface, and then adding their contributions to the liquid. Only droplet-vapor heat transfer is included in the model. The flow, temperature, and interfacial mass flux predicted by the model are presented. The ullage pressure is compared against experimental data obtained from the MHTB spray bar mixing experiment.

Numerical Study of the Influence of Ambient Pressure on the Inerting Effect of an Aircraft Fuel Tank Inerting System

Abstract: The numerical study of the influence of the ambient pressure of the fuel tank on the inerting effect of an aircraft fuel tank inerting system was carried out. The mathematical model of ullage equilibrium oxygen concentration has been established using the differential time calculation method based on the mass conservation and ideal gas state equations. The variations of ullage oxygen concentration and dissolved oxygen concentration in the fuel with time under different working conditions have been obtained. The results have shown that the as the ambient pressure of the fuel tank became lower, the speed of the decreasing of oxygen concentration of the fuel tank ullge and the dissolved oxygen concentration of the fuel was slower.

System and method for reduced flammability of an aircraft fuel system

Abstract: Disclosed is a method for controlling the flammability of fuel vapors in an aircraft main fuel tank that is located in whole or in part in the fuselage contour The method comprises a fuel system architecture and fuel consumption sequencing maintaining liquid fuel in said main tanks during all normal operations Ceasing the withdrawal of fuel from the main tank when the fuel reaches a predetermined level thereby limiting the volume and flammability exposure time of the fuel vapor ullage Once the predetermined level is met the fuel is supplied from wing tanks throughout the remainder of the mission The predetermined main tank fuel level at which wing tank fuel begins to be consumed is determined by the aircraft flight reserves fuel volume stored in the main tank as well as the amount necessary to continuously submerge the main tank fuel pumps during the entire mission

The Oxygen Concentration Measurement of an Aircraft Fuel Tank Inerting System

Abstract: There are several oxygen concentration measurement methods applied in aircraft fuel tank inerting systems. In this work, an aircraft fuel tank inerting experiment system was built and oxygen concentration of the fuel tank ullage (fuel tank space above the surface of the fuel which is filled with fuel vapor and air) and the dissolved oxygen in the fuel was detected with the methods of light absorption and optical fluorescence. The experiment was conducted through different operating conditions and results has illustrated that the light absorption method as well as the optical fluorescence method has the same accuracy sensing calibration gases, but the suitable condition of the two methods are different. Results have shown that the method of light absorption is more suitable to test oxygen concentration of gas mixture, and the method of optical fluorescence is more suitable to detect the concentration of dissolved oxygen in liquid substance.

Modeling of Ullage Collapse Within Rocket Propellant Tanks at Reduced Gravity

Abstract: Orbital maneuvers of upper-stage rockets may generate propellant slosh waves and propellant breakup into droplets within the oxidizer and fuel tanks. When many droplets are created, increased propellant evaporation may occur and lead to a significant reduction in ullage gas temperature and pressure, known as ullage collapse. This work presents a new method that uses a numerical tool to predict the droplet distribution created during a maneuver, and subsequently uses an analytical model to calculate the droplet evaporation and consequent change in tank temperature and pressure. This new hybrid method uses less computational time than a detailed computational fluid dynamics model and is capable of providing mission planners with an improved tool to assess the impact of propellant evaporation on the requirements of additional helium mass for tank repressurization. The new method is applied to predict evaporation and the consequent ullage collapse in an upper-stage propellant tank undergoing simulated orbital...

System and method for storing and transporting low-temperature liquid air

Abstract: The invention discloses a device for stably storing liquid air (a low-temperature mixture of about 80 percent of liquid nitrogen and 20 percent of liquid oxygen) into a storage container. A heat exchanger is provided, the heat exchanger is communicated with evaporative liquid air fluid inside the container, so as to condensate the evaporative liquid air into a fluid form. As a result, nitrogen-enriched steam is condensed and converted into fluid, so that the pressure of ullage is alleviated, the inclusion is cooled, and oxygen enrichment caused by evaporation is prevented finally. A refrigerator can be mounted outside the container and communicated with the fluid inside the container, so as to condense evaporative liquid air inside the container. By being connected to a building HVAC system and/or mounted on a vehicle, the system can be used for oxygen supply or input to a safe refuge area in a mine or a building.

Pressure-Volume-Temperature (PVT) Gauging of an Isothermal Cryogenic Propellant Tank Pressurized with Gaseous Helium

Abstract: Results are presented for pressure-volume-temperature (PVT) gauging of a liquid oxygen/liquid nitrogen tank pressurized with gaseous helium that was supplied by a high-pressure cryogenic tank simulating a cold helium supply bottle on a spacecraft. The fluid inside the test tank was kept isothermal by frequent operation of a liquid circulation pump and spray system, and the propellant tank was suspended from load cells to obtain a high-accuracy reference standard for the gauging measurements. Liquid quantity gauging errors of less than 2 percent of the tank volume were obtained when quasi-steady-state conditions existed in the propellant and helium supply tanks. Accurate gauging required careful attention to, and corrections for, second-order effects of helium solubility in the liquid propellant plus differences in the propellant/helium composition and temperature in the various plumbing lines attached to the tanks. On the basis of results from a helium solubility test, a model was developed to predict the amount of helium dissolved in the liquid as a function of cumulative pump operation time. Use of this model allowed correction of the basic PVT gauging calculations and attainment of the reported gauging accuracy. This helium solubility model is system specific, but it may be adaptable to other hardware systems.

Fuel tank arrangement for liquefied gas in a marine vessel

Abstract: The invention relates to a fuel tank arrangement (10) comprising a tank container (12) for liquefied gas in a marine vessel (16), which is arranged to endure internal pressure above the atmospheric pressure and which is provided with heat insulation on outer surface of the container, and the tank when containing liquefied gas in use includes a liquefied gas space and an ullage space, and in which arrangement a communication junction for liquefied gas is arranged to communicate with the inner space of the container. The communication junction (40,41) is arranged to serve as a coupling means for gas lines (27,28) of the arrangement, and that the communication junction is connected to the tank container.

System and method for supplying ink to an inkjet cartridge

Abstract: In a system and method for operating an ink supply to an inkjet cartridge, wherein the ink supply includes an ink reservoir and an ink tube, ink in the ink reservoir is coupled to ink in the ink tube. Ullage above the ink in the ink reservoir is coupled with ullage above the ink in the ink tube. Ink from the ink tube is supplied to the inkjet cartridge.

Sinda/Fluint Stratfied Tank Modeling

Abstract: A general purpose SINDA/FLUINT (S/F) stratified tank model was created and used to simulate the Ksite1 LH2 liquid self-pressurization tests as well as axial jet mixing within the liquid region of the tank. The S/F model employed the use of stratified layers, i.e. S/F lumps, in the vapor ullage as well as in the liquid region. The model was constructed to analyze a general purpose stratified tank that could incorporate the following features: Multiple or singular lumps in the liquid and vapor regions of the tank, Real gases (also mixtures) and compressible liquids, Venting, pressurizing, and draining, Condensation and evaporation/boiling, Wall heat transfer, Elliptical, cylindrical, and spherical tank geometries. Extensive user logic was used to allow for tailoring of the above features to specific cases. Most of the code input for a specific case could be done through the Registers Data Block.